Penguins who call Phillip Island home are much healthier than their St Kilda cousins St Kilda's famous penguin colony is suffering from the poor health of Port Phillip Bay, with researchers finding the penguins carry high levels of arsenic, mercury and lead in their blood.
The levels are much higher than those in penguins who live on Phillip Island and the remote Notch Island colony in Bass Strait.
Although the levels are not high enough to cause concern for their long-term health, researchers from Victoria University have pointed the finger at the controversial practice of dredging in the bay for the penguin's health.
Researchers believe dredging has disturbed and moved polluted sediment which has then led to contaminated particles to enter the penguin's food source.
Victoria University PhD candidate Annett Finger, who led the research, said: "While the source of the increased blood mercury is unknown, we do know that Port Phillip Bay went through major dredge works from 2008 to 2009".
"It is a potential contamination hotspot because it is quite shallow and closed off – historically polluted sediments are still there, they don't get flushed out."
Dredging was introduced across Port Phillip Bay in 2008 to lift sediment off the bottom of the bay to allow boats to enter shallow waters.
The Environmental Protection Authority introduced broader water quality monitoring during the dredging period, which ended in 2011, and for two years following.
A spokesman for the Department of Environment, Land, Water and Planning said it was common for differencing levels of contaminants to occur and that current levels are not high enough to be concerned about.
"The penguins using the St Kilda breakwater as their home are unique in their occupation of artificially constructed habitat and unlike the penguins from Phillip Island spend their lives in the bay," he said."The St Kilda population has steadily increased since the breakwater was built for Melbourne's 1956 Olympic Games."
Ms Finger, who studies at the university's Institute for Sustainability and Innovation, tested 300 of the furry little penguins were tested as part of a three-year study to see if their own health reflected that of the waters they swim in.
The penguins feathers, blood and faeces were collected and analysed, with researchers finding that the levels of chemicals in the St Kilda penguins were much higher than those in Phillip Island.
About 1000 little penguins live at St Kilda.
"St Kilda's little penguins feed only within the bay so this was a unique opportunity to find out how contaminated their marine environment is," she said.
Ms Finger hopes the toxicology study will help future plans involving the bay's management and conservation.
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